Overcurrent Protection

Most of Article 240 in the National Electrical Code (NEC) provides general requirements for overcurrent protection and overcurrent protective devices not more than 1,000 volts (V), nominal. As a general rule, the overcurrent device rating shall not exceed the ampacity of a conductor.

Recently, a question came up regarding installing overcurrent protection for dry-type transformers rated less than 1,000 volts (V). The transformer installation is a 150-kilovolt-ampere, three-phase unit with a 480V primary and a 208Y/120V secondary.

If you have a problem related to the National Electrical Code (NEC), are experiencing difficulty in understanding a Code requirement, or are wondering why or if such a requirement exists, ask Charlie, and he will let the Code decide. Questions can be sent to codefaqs@earthlink.net.

If you have a problem related to the National Electrical Code (NEC), are experiencing difficulty in understanding a Code requirement, or are wondering why or if such a requirement exists, ask Charlie, and he will let the Code decide. Questions can be sent to codefaqs@earthlink.net.

If you have a problem related to the National Electrical Code (NEC), are experiencing difficulty in understanding a Code requirement, or are wondering why or if such a requirement exists, ask Charlie, and he will let the Code decide. Questions can be sent to codefaqs@earthlink.net.